freemani maple – spindle gall and black spot

(Question)

– I live in Kitchener (Zone 5)
– I have clay soil
– I think that the soil is on the alkaline side
– house built in the 1960’s

-planted a Freemani maple (red X silver) about 3 years ago in full sun
– unfortunately, the Freemani maple was root bound so I made sure to break a good number of the roots before planting to encourage the roots to spread

– looks generally very healthy
– good rate of growth (it’s about 12′ now)
– lots of new leaves emerging
– seems securely rooted
– turns a nice fall colour (red)

– I didn’t water it as much as I probably should have last summer (and it was quite a dry summer)

– this spring, I noticed that some (not many) of the leaves, especially on one of the branches, had some thin protrusions (spindle gall? – I think) on the upper side of the leaves
– I removed the affected leaves that I could see and reach over the course of a few of weeks and now (start of summer) I can no longer see any leaves with these protrusions
– now I notice that some leaves (not many) seem to have a dark brown spot, that is slightly lighter in the center (black spot?)
– also, a few (not too many) of the new emerging leaves are curled, disfigured and have black on them (I have removed those that I can see)

ASIDE:
– please note, that the freemani maple was planted in a different spot in our backyard one year after a huge silver maple was removed from our backyard
– we would have kept the big old silver maple, but it had been topped by the previous owner and the topping had weakened the limbs and there was a fair bit of decay, but otherwise looked very healthy
– after we cut down our silver maple, we noticed that the silver maple must have had a few leaves (next to none) that had black spot

BACK TO OUR FREEMANI MAPLE:
– also note, the Freemani maple has 2-3 minor splits in the bark of the trunk
– unsure why?
– I think there was one split there when we bought it? the other two might be due to sun scald possibly???
– it has a small fence around it, so it’s not from lawnmower damage

– we really like the tree, really like the fast rate of growth, really like the fall colour – want to help it…want to keep it…should we be concerned?…does it stand a chance?…does the extremely wet spring have anything to do with some of these problems?

(Answer)

 

Thanks for your inquiry. Your tree sounds beautiful and it is obvious that you want to take good care of it.  The leaves may be infected with one of the following diseases.  I would suggest you retain the services of a licensed arborist who can exam your tree and if necessary remove the infected branches.

Phyllosticta (Phyllosticta minima) causes spots to appear on the maple tree’s leaves. Spots commonly appear either singular or irregular in appearance. The coloring is normally a dark brown to a tan. The margin of the spots usually appears darker than the center. Often darker, black spots appear within the main spot. If the infection is severe and widespread then the infected leaf will die and fall from the tree. Trees are infected in the early spring by airborne spores. It is imperative that infected leaves be promptly raked up and removed from the area to prevent the spread of the disease to other trees. Bordeaux fungicides can be used to gain control of the disease.

Leaf Wilt ( unlikely)

Leaf wilt, also known as maple wilt, is caused by an infection called verticillium. This infection enters the tree by the roots, then spreads upward into sapwood and leaves. Usually the first sign of this infection are scorched, discolored and brown leaves. Branches at the crown of the tree may also start to die off, and the sapwood of the tree–the wood underneath the bark that is carrying nutrients up through the tree–may show olive-green streaks if you cut down to it. Control leaf wilt in its early stages by pruning the infected branches with a sterile instrument. Fertilize your red leaf maple and keep it well-watered, since your tree will need to establish new nutrient pathways so that it can avoid the infected wood entirely, thereby eventually killing the fungus. If the fungus has taken over large portions of your tree, then you will likely need to remove the tree entirely to prevent a wider infestation.

Tar Spot

This fungal infection causes large, black circles to appear on the leaves of the red leaf maple. However, while this is certainly cosmetically unappealing, this infection does not tend to harm the tree. Control the infection by removing affected leaves and branches if necessary. This should remove the issue by the next growing season. However, if you start to notice serious leaf drop, attack the problem with a fungicide.

Leaf Scorch

Leaf scorch of the maple tree is believed to be caused by the environment. Nutritional deficiencies, soil problems, salt, drought and other toxins cause the maple tree’s leaves to begin drying. The margins of the leaves will appear brown but the inside of the leaf often remains green. Leaf drop is common. Diseased areas should be pruned to reduce the spread of the problem. The source of the situation needs to be discovered and rectified in order to restore overall health to the maple tree. Extensive watering of the tree can help the situation. Proper fertilizing is also important.

Barking splitting:There is no single reason for bark splitting on trees. During late winter and early spring, severe cold followed by rapid thawing can result in splits referred to as “frost-cracks.” These “frost” cracks can actually start from a wound inflicted earlier in the tree’s development. Sometimes the crack may remain in the internal wood, but frosts can cause the crack to expand and split the bark. Excessively late growth in the fall, stimulated by warm temperatures, high humidity and high nitrogen levels, can increase susceptibility of trees to frost cracking.

Fluctuating growth conditions may also cause splitting of bark. Dry weather (which slows growth) followed by wet or ideal growth conditions may cause an excessive or vigorous amount of growth leading to splits in the bark.